Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the agent knows this is a safe read against live external data. The description adds only parameter caps (default 10, max 20) and no return-format, latency, or rate-limit context beyond that, so with annotations carrying the safety profile a 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose and routed to the alternative, with no wasted preamble. It loses a point for redundantly repeating the limit default/maximum twice — once in the opening sentence and again in the parameter list.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter read tool with an output schema, full annotation coverage, and 100% schema description coverage, the description supplies everything an agent needs to invoke it and route correctly. Only minor behavioral detail (what a suggestion entry looks like, ordering) is absent, which the output schema presumably covers.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both parameters are already documented in the schema. The description restates the same limit bounds and query meaning ('Shop.app search keywords, e.g. sneakers') without adding syntax or edge-case guidance, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Returns Shop.app autocomplete suggestions') and explicitly contrasts itself with the sibling shop_app_search, which searches products. An agent can distinguish the autocomplete/suggestion role from the search role without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It names the alternative tool and the condition that selects it ('Use shop_app_search to search Shop.app products'), making the routing decision clear. It stops short of stating when-not to use this tool or that it is intent/typeahead-only, so it is clear but not exhaustive.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.